Invasive Cuban Tree Frogs in Florida

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A report by Jane Weber for the Citrus County Chronicle.

Florida has around 30 species of native frogs in five families. Florida has eight species of arboreal tree frogs in the family Hylidae, but only four occur in Citrus County. One alien invader eats five species of our native frogs as well as small lizards and beneficial garden snakes. All tree frogs have enlarged, sticky toepads.

Invasive Cuban Tree Frogs, Osteopilus septentrionalis, were accidentally introduced to Florida in shipping and packing materials in 1920s. Since then, these large tree frogs have become a bothersome alien pest throughout Florida, especially in subtropical South Florida. Locally they are an increasing serious problem in Citrus and Marion County. Cuban Tree Frogs have been transported on plant shipments from Florida as far as Canada, Oahu in Hawaii and Wisconsin.

Cuban Tree Frogs are originally from the Bahamas, Cayman Islands and Cuba. Their tadpoles compete for space and food with native frogs, which are already heavily impacted by habitat loss and human development. Reaching up to five inches long, these aliens are variable in color from brown, gray, green or white, and can change colors. Skin color may be solid, streaked or splotched. Their skin exudes a slime to protect them from drying out and is a deterrent to predators. This slime also irritates sensitive human tissues. Wear gloves or use a plastic bag when capturing these problem pests.

Seeking warmth and dark hiding places in utility boxes and switches, large Cuban Tree Frogs are known to cause expensive power outages. Smaller native tree frogs have not been found causing utility problems. Tree frogs feed at night, so are attracted to insects around lights left on at night. Cuban Tree Frogs have been documented in birdhouses, decorative ponds, birdbaths, among foliage of potted plants and frequently on walls where they can leave messy stains and droppings. Big tree frogs can enter homes via drains and vents and show up in toilets or clog drains.

Johnson recommends capturing and humanely euthanizing Cuban Tree Frogs by applying benzocaine to the frog’s back or belly. It is both illegal and irresponsible to relocate wildlife. Over-the-counter gels and liquid products containing 20 percent benzocaine are readily available from drugstores. Within minutes of application, the Cuban Tree Frog loses consciousness. Then it can be put in a bag and into the freezer overnight where it dies quickly and painlessly.

Dr. J emailed me to say “another humane method, which is less trouble, is to simply use a plastic sack over your hand as a glove and grab the invasive Cuban Tree Frog. Be deliberate and decisive and don’t be timid when grabbing them. Turn the back inside out and tie closed, with the frog in the bag. Place the bag in the fridge for two to three hours then transfer to a freezer overnight. The next day toss the bag outside in the trash bin.”

Tree frogs do live alongside humans and have a wide diet of insects, arachnids and small invertebrates including ants, beetles, crickets, grasshoppers, moths, spiders and termites. A Chronicle reader, Ron Egnot of Lecanto, had such a large Cuban Tree Frog infestation last summer he made nightly forays into his garden to squirt benzocaine on the alien pests. They congregated in prized palms near Ron’s home, waiting to prey on insects that came to feed on flower nectar, pollen and ripe fruit drupes. The observant homeowner noticed there were no longer any native tree frogs in his garden as the invaders had preyed on native tree frogs too. The added pressure, predation and competition for food has contributed to the decline of native species and their natural habitats.

Citrus County’s four insectivorous, native tree frogs are:

Green Tree Frog, Hyla cinerea, 1 to 2 inches, bright to dark green, sometimes grayish with smooth skin.

Pine Woods Tree Frog, Hyla femoralis, 1 to 1.5 inches with blotched skin of variable colors from brown, gray, green or tan.

Barking Tree Frog, Hyla gratiosa, 2 to 2.5 inches, plump with uniformly “goose-bumpy” skin in gray, green or brown.

Squirrel Tree Frog, Hyla squirella, 1 to 1.5 inches, of variable color, brown, gray, green or tan, and a mask on the face.

Visit Dr. J’s Johnson’s Lab online to learn more at http://ufwildlife.ifas.ufl.edu/cuban_treefrog_inFL.shtml. He has some great pictures.

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